JPS63192074A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the deterioration in image quality due to electrostatic charger tracking caused by corona products to obtain images of high quality by forming a toner layer on an image carrier before image forming and scraping away the toner layer. CONSTITUTION:A developing device 5 is used to a coat a toner on a part of a photosensitive body, especially, a part facing a charger 3 or a part facing chargers 7 and 8 according to circumstances, and thereafter, the toner is scraped away by a cleaning device 9. Thus, corona product stuck to the surface of the photosensitive body 1 are scraped to prevent the occurrence of charger tracking,and images of high quality free from charge tracking are obtained even at high humidity and in a nonconductive state.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus using an electrophotographic method, such as an electrophotographic copying machine or an electrophotographic printer.

I As is well known to those skilled in the art, an image forming apparatus using an electrophotographic method includes an image carrier such as an electrophotographic photoreceptor, and the purpose of applying an electric charge to the image carrier to form a latent image. It has a charging (discharging) device such as a corona charger arranged for this purpose. Generally, the image carrier is movable in the form of a belt or a drum, and the charging device is fixedly arranged around the image carrier.

In an image forming apparatus having such a configuration, when the image forming operation is completed, the image bearing member stops, but corona products attached to, for example, a shield plate are gradually released from the charging device into the atmosphere while the charging device is in operation. If this condition is maintained for a long time, corona products will adhere to the part of the image carrier facing the charging device, causing longitudinal image drift called "charger marks". This may occur and reduce the quality of the image. This phenomenon is particularly noticeable in high humidity environments.

In particular, in an image forming apparatus configured to control the temperature of the image carrier, the image forming apparatus is stopped and electricity is turned off.
In the case of FF, the temperature control device of the image carrier is also turned off, and the temperature of the carrier itself drops to about room temperature, resulting in a phenomenon in which the charger trace flow increases.

Conventionally, in order to suppress the adhesion of corona products to the surface of an image carrier, which is a major cause of such image blur, a method has been proposed in which the area around the charging device is forcibly ventilated.

However, this method can significantly reduce the ozone concentration around the charging device while the image forming device is in operation, and the adhesion of corona products to the photoreceptor can be suppressed.
Although this method has been highly effective as a measure to prevent image blurring under high humidity conditions, it has not solved the problem that occurs when the image forming apparatus stops operating, as described above.

The present inventors have found that the above problem can be solved by applying toner to the image bearing member prior to image formation on the image bearing member and then rubbing (cleaning) the surface of the image bearing member. . Furthermore, it has been found that in a device for controlling the temperature of an image bearing member, by increasing the amount of heat of the temperature control device during preliminary operation, it is possible to obtain an image without charger traces even under high humidity.

Further, according to the present invention, in addition to preventing image deletion due to charger traces, the present invention can also prevent image formation by repeating the process of forming a transferable toner image on the surface of an image carrier and then transferring the image to a transfer material. In devices, foreign substances such as talc, rosin, etc. precipitated from transfer materials, mainly paper, adhere to the image carrier, causing a decrease in the surface resistance of the image carrier. It turns out that image blur can also be solved. Particularly, in an image forming apparatus using a photoreceptor such as amorphous silicon or OPC as an image bearing member, the present invention is capable of preventing electrostatic discharge from the charging device that occurs after the image forming apparatus is stopped from occurring to the surface of the image bearing member. It is an object of the present invention to provide an image forming apparatus capable of obtaining high-quality images by preventing deterioration in image quality due to charger traces caused by corona products.

Another object of the present invention is to prevent foreign matter such as precipitates such as talc and rosin deposited from the transfer material onto an image carrier in a transfer-based image forming process using a transfer material mainly made of paper. An object of the present invention is to provide an image forming apparatus capable of preventing adhesion and obtaining high quality images.

The above object is achieved by an image forming apparatus according to the present invention. To summarize, the present invention includes an image carrier, a charging device arranged to form an electrostatic latent image on the image carrier, and a developing device for visualizing the electrostatic latent image on the image carrier. The image forming apparatus is characterized in that, prior to image formation, a toner layer is formed on the image carrier using the developing device, and then the toner layer is removed by rubbing. This is an image forming apparatus. Also, preferably,
The apparatus includes a heating means for heating the image carrier and a detecting means for detecting the humidity of the atmosphere, and is configured to measure the humidity when the power is turned on and control the electric power of the heating means in accordance with the measured value.

Train 1 Next, the image forming apparatus according to the present invention will be explained in more detail with reference to the drawings.

FIG. 1 shows an embodiment in which the present invention is embodied in an electrophotographic copying machine. A charger 3, an exposure section 4, a developer 5, a transfer charger 7, a separation charger 80, a cleaning device 9, and the like are arranged around the charger 1. Since such a configuration is well known to those skilled in the art, further detailed explanation will be omitted.

The surface of the photoreceptor 1 is uniformly charged by a charger 3, and then an electrostatic latent image is formed by irradiating a light image from an exposure unit 4.Next, the latent image on the photoreceptor 1 is transferred to a developer 5. The toner image is transferred to a transfer material 6 such as paper by the action of a transfer charger 7.

After the transfer, the transfer material 6 is separated from the photoreceptor l by a separation charger 8.

On the other hand, residual toner remaining on the photoreceptor l without contributing to transfer is removed by a cleaning device 9.

The cleaning device 9 includes a cleaning blade IO and an elastic roller 11, and residual toner on the photoreceptor is mainly scraped off by the blade 10 and stored in the cleaning device, and is transferred to the screw conveyor 1 as needed.
The residual toner removed by the zero elastic roller 11 which is discharged to the outside by the roller 3 is scraped off by the blade 12 that is in contact with the elastic roller 11, and is conveyed to the screw conveyor 13. The photoreceptor 1 from which the residual toner has been removed is exposed to the front fog light 2.
After receiving the irradiation, it is subjected to the image forming process again.

In an image forming apparatus with such a configuration, "charger traces" that cause image smearing can be avoided by stopping the image forming apparatus, especially in a high humidity environment, and stopping the rotation of the photoreceptor and the operation of the charger for a long period of time, such as overnight. It has been confirmed that this occurs on the part of the photoreceptor facing the charger when

According to the present invention, the image carrier, that is, in this embodiment, a part of the photoreceptor 1, particularly the charger 3. In some cases, charger 7.8
The developing device 5 is used to coat the part of the photoconductor facing the toner with toner, and the toner is then transferred to the cleaning device 9.
It is designed to be removed by rubbing. With this configuration, corona products adhering to the surface of the photoreceptor 1 are scraped off, thereby preventing the occurrence of flow in the charger path. At the same time, according to the configuration of the present invention, foreign substances such as precipitates such as talc and rosin in the transfer material, which are deposited from the transfer material and adhered to the photoreceptor, are removed from the surface of the photoreceptor l.

Next, an example of coating toner on the photoreceptor l will be described. FIG. 2 shows a sequence in which toner is applied to the photoreceptor by adjusting the developing bias applied to the developing device 5. As shown in FIG.

Let tAn be the time when the photoreceptor l starts, and let tAn be the time when arbitrary points A and B on the surface of the photoreceptor that are separated from each other pass the developing device position P point for the nth time after the photoreceptor starts rotating. , tBn, and by turning on the developing bias only between times tAn and tBn, a toner layer can be formed between AB. Of course, such an operation is performed before the pre-rotation performed prior to the image forming operation of the photoreceptor l is completed.

FIG. 3 shows a sequence in which toner is similarly applied by adjusting the developing bias after charging the surface of the photoreceptor.

Next, the embodiments shown in FIGS. 2 and 3 will be described in more detail. As the photoreceptor l which is an image carrier, it is directly [108 mm
1 elastic roller 1 using an amorphous silicon photoreceptor of
1, a sponge layer was provided on the core metal, and the outer layer was a silicone rubber layer with a thickness of 1.2 in., and the diameter was 20 m.
m was used. The elastic roller 11 was pressed against the photoreceptor 1 with a pressure of about 400 g.

In the embodiment shown in FIG. 2, the developing bias is Dc-i.
o ov was applied. In the embodiment shown in FIG. 3, the photoreceptor l is charged to +200V by the primary charging base 3, the developing bias is +100V as a DC component in the area where toner is to be applied, and the photoreceptor is applied to the area where toner is not applied. Body potential plus 200 V, that is, 400 V, and an AC component of 1800 Hz and 1400 Vpp were applied as a developing bias to both the toner-applied area and the toner-unapplied area.

In this example, the developing bias is set at a humidity of 7.
It was set to operate when the ratio is 5% or more, and not to operate when the ratio is less than 5%. Further, in this embodiment, the photoreceptor 1 has a temperature adjustment device, that is, a photoreceptor heating device, and the photoreceptor heating device has heaters of 100W and 300W, and the temperature and time when the photoreceptor is heated by each heater are adjusted. The relationship between the two was as shown in Figure 4.

In such a configuration, if the copying machine is left overnight without electricity, the humidity of the atmosphere is measured when the power is turned on, and the wattage of the heating device is determined according to the result. The temperature was 32°C and the humidity was 85%, so a 300W heater was used. As shown in Figure 4, the temperature of the photoreceptor reached 47.7°C after 1.5 minutes.
(overshoot), then gradually decreases,
Approximately 4 during standby (wait up) 5 minutes after power on
It became 6℃.

When an image was formed with this configuration, the charger trace completely disappeared and a high quality image was obtained.

As can be understood from the above embodiments, when the humidity is high, in addition to eliminating the afterflow of the charger by toner coating and rubbing, increasing the heat amount of the heating device accelerates the rise of the photoreceptor temperature and sets the temperature. It is possible to take a longer time from reaching the value to the weight-up, and it also contributes to the recovery of the charger trace flow due to the increase in surface temperature due to overshoot (this increases as the amount of heating heat increases). are doing.

On the other hand, at normal humidity of 60%, the heating device is
The temperature of the photoreceptor is adjusted at 0°W. In such an environment, charger traces are unlikely to occur, so it is only necessary to reach the set temperature before the weight is increased.

Heating heat f of the heating device at humidity between 85% and 60%
It (power) can be controlled in stages using phase control, for example, or
It can be changed continuously. Furthermore, after a certain period of time has elapsed after the weight-up, the temperature inside the copying machine generally rises due to internal temperature rise, so even if continuous copying is performed, the temperature drop of the photoconductor will be small, so the heating device It is okay to lower the amount of heating heat.

In the above embodiment, the toner layer is formed on a part of the photoreceptor, but the same effect can be obtained by forming the toner layer on the entire surface of the photoreceptor.

``Mamejisashij'' As explained above, the image forming apparatus according to the present invention applies toner to the image bearing member prior to forming one image, and removes the toner, and further heats the image bearing member. By controlling the amount of heating heat of the device, it is possible to obtain high-quality images without charger traces even when the device is placed in a high-humidity, non-energized state.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of an image forming apparatus according to the present invention. FIG. 2 is a sequence diagram when an image carrier is coated with toner using only a developing bias. FIG. 3 is a sequence diagram in the case where toner is applied by a developing bias after the image bearing member is charged. FIG. 4 is a diagram showing the relationship between the surface temperature of the image carrier and time after the recording is performed. l: Image carrier 3: Charger 5: Developing device 6: Transfer material 9: Cleaning device 10 Blade 11: Elastic roller

Claims (1)

[Scope of Claims] 1) An image carrier, a charging device arranged to form an electrostatic latent image on the image carrier, and a developing device for visualizing the electrostatic latent image on the image carrier. In the image forming apparatus, the toner layer is formed on the image carrier using the developing device prior to image formation, and then the toner layer is removed by rubbing. Features of the image forming device. 2) Equipped with a heating means for heating the image carrier and a detection means for detecting the humidity of the atmosphere, and measuring the humidity when the power is turned on;
The image forming apparatus according to claim 1, wherein the electric power of the heating means is controlled according to the value.